Biodiversity as insurance


Diversity buffers against changes

No one species fills all the roles (functions) of an ecosystem (species diveristy)
No one individual has all the alleles for a gene (genetic diversity)

Today’s topic: Species Diversity



  • Intricate webs of interacting organisms
    • 2,000,000 species are known
    • ~18,000 new species discovered per year
    • estimated >85% of species unknown


  • Reflects billions of ways organisms have adapted, over and over, to a changing planet
    • biodiversity ’hot spots” exist


  • Humans relentlessly alter ecosystems
    • aquatic and terrestrial
    • ~150 species go extinct each day

HOW: Measuring biodiversity (e.g. Simpson’s index)


Assumption: All species are equally important

Richness and Evenness both contribute to functional diversity


WHO: Species types (native, endemic, non-native, invasive)


The march of the cane toad


Where: Species diversity declines from tropics


Where: Species diversity declines at altitude


Mapping biodiversity: Soil community diversity matters


Mapping biodiversity: Oceans


Ecoregions: Where biodiversity hotspots exists


Hotspots: Andean uplift and bird diversity


Hotspots: Endemic species of Madagascar


What factors contribute to 90% endemism?

Threats to biodiversity


Threats: Invasive species are increasing






  • Change physical and biotic environment



  • Aquatic ecosystems heavily affected



  • Impacts outweigh natural extinction rates

Ecoregions versus humans


Biodiversity is decreasing rapidly (Living Planet Index 2022)